Question #11baf
1 Answer
They are not volatile enough to produce one.
Explanation:
Odour is the result of the compound vaporising, or at least being a gas, so that your olfactory system is capable of detecting it. If a compound is not so volatile that it vaporises at room temperature, it will not give off an odour. Take diamond as an example. Composed entirely of strong covalent bonds, it will not vaporise and so no odour is given off.
We cannot smell certain substances simply because our olfactory systems are not equipped to detect them. For example, we must add an odorant to methane, or natural gas, as a safety mechanism because we cannot pick up on it ourselves. Similarly, at the typically low concentrations at which is is found, carbon dioxide is odorless; however, at high concentrations it exhibits a sharp, acidic odour.
To summarise, odour is dependent on two factors: the ability of the compound to vaporise / be a vapour, and the ability of the human olfactory system to detect that vapour.
